Characterization of functionalised porphyrin films using synchrotron radiation

Porphyrins and C60 are strategic materials for the fabrication of nanoscale molecular devices by virtue of their optical, photo-electro-chemical and chemical properties. We have developed procedures to immobilise cobalt tetra-butyl-phenyl porphyrins (CoTBPPs) on gold surfaces via ligation to self-assembled monolayers of aromatic aminothiophenols (4-ATP). We have used synchrotron radiation photoemission and near-edge X-ray absorption, NEXAFS, to characterise such films, both in their native state, and with ligated fulleropyrrolidines N-methyl-2-(p-pyridyl)-3,4-fulleropyrrolidine (Py-C60), forming charge-separation complexes which may have applications in solar cells. While photoemission spectra appear dominated by the individual CoTBPP and Py-C60 components, we observe an apparent signature of charge separation in fulleropyrrolidine NEXAFS spectra.